Air cooling system for railway cars



NOV. 1, 1938. F FRESE 2,135,125

AIR COOLING SYSTEM FOR RAILWAY CARS Filed Feb. 5, 1956 if the circuitsof all of said motors.

Patented Nov. 1, 1938 um'rso STATES PATENT OFFICE Joseph F. Frese,Baltimore, Md., assignor to Monitor Controller Company, Baltimore, Md.,

a corporation of Maryland Application February 5, 1936, I Serial No.62,511

8 Claims.

This invention relates to an electrically oper ated refrigerating systemfor railway cars. The refrigerating mechanism comprises a compressor, areturn pipe system connected to the compressor and including a condenserand a refrigerating coil. A direct current motor is provided foroperating the compressor, a plurality of motors are provided forcirculating cooling fluid around the condenser and a single starter isprovided. for starting and stopping all or" said motors so that thecompressor motor cannot be operated Without the operation of thecondenser motors. A control circuit is provided for controlling thestarter, this circuit including a thermostat switch which opens andcloses the circuit in accordance with the temperature in the car, andcertain safety switches which open the circuit under abnormalconditions. The opening of any switch in the control circuit causes thestarter toopen A fan motor for circulating air in the car past thecooling coil is operable independently of said control circuit and ofthe voltage of the'hattery.

The invention comprises also means for charg I ing the battery andoperating the refrigerating apparatus while the car is stationary bymeans of an alternating current motor which may he connected to a powerline and which operates the compressor motor as a generator to chargethe battery through the starter, ates the compressor.

Referring to the drawing, in which. the inven tion is illustrateddiagrammatically, A represents a generator adapted to be operated fromthe car axle and B indicates a battery which receives its charge fromthe generator. As the generator operates at variable speeds, a suitablevoltage regulator c is provided for varying the resistance in the fieldcircuit of the generator to limit the max'imtun. voltage of thegenerator and maimtain it constant at a suitable charging value. Acontactor d is provided for connecting the armature circuit of thegenerator to the battery and the magnet coil i of this contactor isconnected in a circuit :23 across the armature terminals of thegenerator, which circuit is controlled by a reverse current relay c.This relay closes the circuit 2-3 when the generator voltage is abovethe battery voltage and opens said circuit when the generator voltagefalls below the battery voltage. When the circuit 23 is closed, thecontactor arm 4 connects one brush of the generator to one side of thebattery through conductors li-6. The other brush of the generator isconnected to the opposite side of the battery and also operthroughconductor 2 and a coil of the reverse current relay. Supply wires L andIF, respectively, lead from the opposite poles of the battery and tothese wires are connected the circuits of the various motors and motorcontrolling devices. v

A refrigerator system is shown in outline comprising a compressor Fwhich circulates'fluid refrigerant through a pipe system i which includes a condensing coil a refrigerating coll l3 and an expansion valveto. A direct current motor G operates the compressor and two directcurrent motors H and I are shown for clrculating cooling fluid, whichmay he liquid or air, around th condensing coil, and a direct currentmotor J is shown for circulating the air in the car around and past thecooling coil 9. An alter-= nating current motor K. is shown. This isdriven idly by the compressor motor G and does no work except when thecar is standing still, when it may be connected to an alternatingcurrent, supply circuit and used to drive the compressor and also drivethe motor G as agenerator to charge the battery, as hereinafterexplained.

The motors H and. are controlled by a common starter S. Thus thearmature circuit of the compressor motor extends from sup ply wire 1 tothevai'inature oi the motor, thence by conductor ll through coil 5 l ofan overload switch in to conductor l2, thence through conductor which iscommon to all of said motors, and resistance sections r, r to arm 56 ofcontactor s, and when this contactor is closed, the armature circuit iscompleted to supply wire L" through conductors and The armature circuitof motor H is iromsup ply wire 3.5 tlu'ough conductors l1 and ill andcoil ill of overload switch a to conductor and thence through the commonconductor and resistance sections to contactor arm l t, conductors 55'and ill, to supply wire L.

ifhe armature circuit of motor I is from supply wire L through conductor69 to the arma-= ture, thence through conductor to coil 20 of overloadswitch 0, thence through conductor E2 to the common conductor lit, theresistance sections, contactor arm 54 and conductors to and it; to thesupply wire L.

The field winding or the compressor motor G is connected in a circuitwhich extends from supply'wire L through conductor 22 to the fieldwinding, thence through conductor 23 to a resistance 2 which isconnected to conductor is and contact arm M and when the cont-actor scloses, this resistance is shunted through con- Eli ductor 23 tostrengthen the field while the compressor motor is starting. After themotor has been started, the contactor s opens and this reinserts thefield resistance 24 in the field winding of the motor. The contactor s,which operates to cut out the section r of the armature resistance, hasits arm 25 connected to the conductor H? by conductor 26 and when thiscontactor closes, the circuit from conductor I3 is completed to supplywire L through conductors 21 and |5, thus cutting the resistance section1" out of the armature circuits of the motors G, H and I. The contactarm 28 of contactor s is connected by conductor 29 to conductor l3 andwhen this contaotor closes, the circuit is completed from conductor l3through conductors 30 and l6'to the supply wire L, thus cutting out theresistance section r from the armature circuit of each motor. Thecontactors s, s and s are controlled so as to operate in sequence and intimed relation by a time-controlled relay t.

The air circulating motor J is controlled so that it may be operatedindependently of the compressor and condenser motors for circulatin theair in the car even when the latter motors are stopped and it is veryessential that the air circulating motor shall be in operation at alltimes while the compressor is in operation in order to avoid overheatingin the system. Therefore, the electrical connections are such that thefan motor may be operated independently of the other motors and must bein operation while the other motors are operating.

An operator's switch P is provided for manually controlling theoperation of the motors. As shown, a contact arm 3| is connected byconductor 32 to supply wire L and this arm may be set in severaldifferent positions. In the-position marked ofi", all of the motors arestopped. In the position marked fan, the contact arm 3| engages a singlecontact 33, which is connected by conductors 34 and 35 to the aircirculating motor J and by conductor 36 to the supply wire L Therefore,when the contact arm is in said position, the motor J will operate tocirculate air past the cooling coil 9 into the car or room. If thecontact arm 3| is moved into the position marked cool, it will engagethe contact 33 and also a contact 31 and through the latter contact acontrol circuit will be completed to cause the operation of thecondenser and compressor motors, providing the temperature of the air inthe car is high enough to cause the closure of a thermostat switch whichis included in said circuit, and also providing certain safety switchesare closed and the battery voltage is above a predetermined value. Theair circulating motor J will operate whether the battery voltage is highor low and independently'of the continuity of the control circuit forthe other motors.

The control circuit for the starter S and motors G, H and I extends fromsupply wire L thro'ugh conductor 32 to contact arm 3| of switch P to,

46 of said switch is connected by conductor 41 to coil 48 oftime-controlled relay t and from said coil the circuit extends byconductor 49 to cona suitable charging speed, the relay d will remain Iopen, but if the generator voltage is above the battery voltage, therelay d will be closed and its contact member 4 will connect thegenerator and one side of the battery through conductor 60 to conductor6| which leads through resistance 62 to coil 63 of the low voltagerelay, and the circuit of said coil continues through resistance 64 andconductor 34 to the contact 33 of switch P and when the switch arm 3| isin engagement with said contact, the circuit is completed to the side Lof the supply circuit through conductor 32. As long as the generatorvoltage is above a predetermined value and the arm 3| of switch P is inengagement with the contact 33, the low voltage relay will remain closedand the control circuit before mentioned will be completedv at saidrelay. If, however, the generator is stopped or is operating at a speedbelow the charging speed, the connection through the conductor 60 to therelay coil 63 will be open at the contactor d. In that event, when theoperator desires to complete the control circuit and start theapparatus, after placing the switch arm 3| in the cool position, hedepresses a reset button 65 which connects supply wire L to conductor GIand thereby completes the circuit through the coil of the low voltagerelay momentarily. If the battery voltage is above a predeterminedvalue, the relay will close and, in closing, will complete a holdingcircuit for its coil through conductor 66, and the relay will remainclosed; but if the battery voltage is below that required for'the safeoperation of the motors, the relay will not close and the controlcircuit will not be completed and hence the motors cannot be up erated.

Assuming the voltage to be high enough for safe operation of the motorsG, H and I, with the operators switch in the cool position and the lowvoltage relay closed, if the thermostat switch, high pressure switchandthe overload switches m, n and o are closed, current will flowthrough-the coil 48 of time-controlled relay t and its contact member 61will be moved gradually upward. This member is connected to theoperator's switch by conductors 68 and 34, and in the first part of theupward movement of said member, it engages a stationary contact 68 whichis connected by conductor 10 to an intermediate point of the resistance64 which is in series with the coil of the low voltage relay andconnected through conductor 34 to the operator's switch. Engagement ofthe member 61 with the contact 69 therefore short circuits a. part ofsaid resistance which results in strengthening the current in the coilof the low voltage relay, so that said relay will not open when a heavydrain is placed upon the battery by the closure of the armature circuitof the compressor motor, as well as the circuits of the condensermotors, which takes place when the member 61 engages the next sta-vtionary contact 1|. When this occurs, the coil of magnet 12 of contactors is energized through a circuit which extends from the operator'sswitch through conductors 34, 68, 13, 5|, 50 and 54 to overload switch111., thence through overload switches 11. and and the low voltage relayto supply wire L Contactor s then closes, completing the circuits of themotors G, H and I through the starting resistance and also cutting theresistance 24 out of the field circuit of the compressor motor tostrengthen its field for starting. The contact member 67 of the relay tnext engages stationary contact 14 and completes the circuit of the coilof magnet 15 of relay .9 through conductors l6 and 52 to conductor 50and thence through the overload switches and the low. voltage relay.Contactor s closes, cutting the resistance section 1" out of thearmature circuits of the motors G, H and I. The contact member -6l nextengages contact 'l'l' and completes the circuit of the coil of magnet 18of contactor s through conductors 1,9, 53 and 50 and thence through theoverload switches m, n and oand the low voltage relay. Contactor arm 28then closes, cutting the resistance section 1' out of the armaturecircuits of the motors andat the same time completing a holding circuit80 for the coil of magnet 18 through stationary contacts 8i and 82 andan insulated contact 83 on the arm 28. In the closing movement of thearm 2%, the circuit to the coil of the time-controlled relay t is openedat the switch 45 and the contact member E! drops downward interruptingthe circuits through the coils of the magnets 0i contactors s and s andthese contactors open, leaving the armature circuit closed through thecontactor In opening, the contactor s breaks the short circuit aroundthe field resistance 24 of the compressor motor so that the latter willoperate at a higher speed. When contact member Bl of relay t leaves thecontact 69, it interrupts the shunt around part of the resistance 64which is in series with the coil of the low voltage relay and thecurrent in said. coil is reduced to normal strength so that the relaywill open if the voltage drops below a predetermined value safe for theoperation of the motors.

If, while the system is in operation, the temperature of the room isreduced to a desirable low limit, the thermostat switch will open thecontrol circuit, and this will cause the magnet 18, which is fed throughits holding circuit 80, to become de-energized and the contactor arm 28will open the circuits to the several motor armatures and its ownholding circuit, and it will close the switch 45 to make up the circuitto the energizing coil of time-controlled relay t. When the temperaturein the room rises sufficiently to cause the thermostat switch to close,the relay t will operate automatically to cause the operation of theseveral motors G, H and I asbefore described.

If excessive pressure occurs in the pipe system in the compression sideof the compressor while the latter is in operation, the high pressureswitch 4! will open the control circuit, causing the magnet 18 to becomede-energized and the contactor s will open the motor circuits and causestoppage of the -motors G, H and I. The high pressure switch will closeautomatically and cause the motors to be restarted when the pressuregoes down if the control circuit is complete at all other points. 7

In case of overload in the armature circuit of the compressor motor G,the coil H will open the overload switch m in the control circuit andthis will cause the contactor s to open the circuits of the compressorand condenser motors and cause stoppage of the same. Similarly, anoverload current in the armature circuit of the motor H will cause coill8 to open the overload switch n in the control circuit and causestoppage of the compressor and condenser motors, and an overload currentin the armature circuit of motor I will cause coil 20 to open theoverload switch 0 and cause stoppage of said motors. As an overload on amotor calls for an investigation of the cause, the overload switches aremade so that they will stay open until closed by hand.

When the car is standing idly in a yard or station and the batterycannot be charged by the generator. A, the alternating current motor Kmay be connected to a power line and used to drive the compressor motoras a generator and also to drive the compressor. For this purpose abranch circuit is extended from the control circuit for operating acontactor W to connect the alternating current motor to the supplycircuit. This branch of the control circuit comprises a conductor 85extending from conductor 5% of the control circuit to a plug 86, and aconductor 87 extending from the conductor 43 of the control circuitthrough the coil 88 of the contactor W to a switch 3/ and from saidswitch conductor tie.

extends to the plug. The motor is shown as a three-phase motor whosecircuits 89, 90 and 9E open switches of the contactor to the plug 86.The terminals of the several conductors attached to the plug are shownprojecting from one end thereof and these terminals are adapted to enterrecesses in a socket 92 to which the wires of a power line are attached.The terminals of the wires 85 and 81 when in the socket, are connectedtogether by a loop 93 which completes the circuit through the contactorcoil when the plug is in the socket and the switch :1; is closed. Thisswitch will be closed if :the phases in the motor circuit are in theproper relation to operate the motor in the desired direction, but willremain open if they are not in such relation, so that extend from themotor through the normallyv it will be possible to operate the contactoronly when the phases are in the right relation. An overload switch a: isarranged in the conductor 87 of the control circuit and coils 94 and 95in the different legs of the motor circuit are adapted to open thisswitch in case the motor K is overloaded.

The contactor W has contact members 95, 9'17 and 98 for closing themotor circuits and a contact member 99 for connecting a conductor Hillto a conductor IDI. Conductor Iiil is connected through conductors l3and 23 and field resistance 24 to the field winding of the compressormotor, and conductor I00 is connected through conductors 23 and 23 tothe field winding. Hence when the contactor closes the circuit betweenconductors I00 and IN, the resistance will be short circuited which willincrease the field strength of the motor, as is desirable when the motoris being driven as a generator.

To start the alternating current motor, the plug 86 is inserted in thesocket 92 and the operators switch lever is placed in the cool positionand the push button 65 is then manually depressed to energize the coilof the low voltage relay. This relay closes and completes the controlcircuit and also its own holding circuit. Current from the battery willthen ,fiow through the branch circuit 85-81 and the coil of contactor Wtor.

circuits of the motor K and will cut the resistance 24 out of the fieldcircuit of the compressor motor G. The motor K will then drive the motorG as a generator and also operate the compressor. The time-controlledrelay t will be energized and will operate as before described to closethe contactors s, s and s in succession and when the last mentionedcontactor closes, it will place the armature circuit of the motor Gacross the battery terminals and also open the circuit of the relay twhich will then return to its normal position, opening the circuit ofcontactors s and s. It will be noted that opening the control circuit atthe switch 45 of contactor s does not affect the flow of current throughthe branch circuit 85-81 to the coil of contactor W, as conductor 85 isconnected to supply wire L through conductors 55, 56, 51, the overloadswitches m, n, and o, and the low voltage relay, and conductor 81 isconnected to supply wire L through the high pressure switch 4|,conductor 40, thermostat 39 and the operator's switch and conductor 32.Therefore, after the closure of the contactor s, the alternating currentmotor will continue to drive the motor G as a generator which willcharge .the battery through the circuit which includes the contactmember of contactor s. The compressor will also be driven mechanicallyby the alternating current motor to which it is connected, and thecondenser motors will operate as they are connected across the terminalsof the motor G and also across the battery terminals. The aircirculating motor J will operate because it is connected across thebattery terminals through the operators switch. It will be seen that allof the switches in the control circuit are in series with the energizingcoil 88 of the contactor W, and should any of these switches open, thecoil 88 will be de-energized, and contactor W will operate to stop thealternating current mo- The holding circuit of magnet 18 of maincontactor s of the starter S is in the control circuit, and when currentin that circuit fails, contactor arm 28 opens and breaks the connectionbetween the armatures of the motors G, H and I and the supply wire Lleading to the battery.

To stop the alternating current motor, the contact arm of the operatorsswitch may be moved off of the contact 31 to interrupt the controlcircuit, which will cause the coil of contactor W to becomede-energizedand the contactor will open the circuits of said motor. Theplug may then be pulled out of the socket 92. While the alternatingcurrent motor is in operation, interruption of the control circuit bythe thermostat switch, the high pressure switch or any of the overloadswitches m, n, or x will interrupt the fiow of direct current to thecoil of contactor W, and this contactor will open the/motor circults,causing stoppage of the motor.

What I claim is:

1. In a refrigerating system, a storage battery,

a supply circuit connected thereto, a motor, a

75 the control circuit when the voltage in the supply series ofcontactors for connecting the motor to the supply circuit and cuttingresistance out of the armature circuit, to start the motor, a

retarded relay controlling said contactors for operation in sequence, acontrol circuit including the-coil of said relay, a low voltage relayhaving an energizing coil, manually controlled means for connecting saidenergizing coil to the supply circuit, said low voltage relay adapted toclose the control circuit when the voltage in the supply circuit isabove a predetermined value and to open circuit falls below said value,and means for strengthening the magnetic field of said low voltage relaywhile the motor is starting and for weakening said field after the motorhas been started.

2. In a refrigerating system, a storage battery, a supply circuitconnected thereto, a motor, a series of contactors for connecting themotor to the supply circuit and cutting resistance out of the armaturecircuit, to start the motor, a. retarded relay controlling saidcontactors for operation in sequence, a control circuit including thecoil of said relay, a low voltage relay having an energizing coll,manually controlled means for connecting said energizing coil to thesupply circuit, said low voltage relay adapted to close the controlcircuit when the voltage in the supply circuit is above a predeterminedvalue and to open the control circuit when the voltage in the supplycircuit falls below. said value, and means controlled'by said retardedrelayifor strengthening the magnetic field of said low voltage relay inadvance of the closure of the first of said contactors and for weakeningsaid magnetic field after the last of said contactors has closed.

3; In a refrigerating system, a storage battery, 3. supply circuitconnected thereto, a motor, a series of contactors for connecting themotor to the supply circuit and cutting resistance out of the armaturecircuit, to start the motor, 'a retarded relay controlling saidcontactors for operation in sequence, a control circuit including thecoil of said relay, a low voltage relay havply circuit is above apredetermined value and to open the control circuit when the voltage inthe supply circuit falls below said value, a resistance normally incircuit with said energizing coil, and means controlled by said retardedrelay for reducing the resistance in circuit with the energizing coil inadvance of the closure of the first of said contactors, and forrestoring the resistance in said circuit to normal after the last ofsaid contactors has closed.

4. In a refrigerating system, a first motor, a second plurality ofmotors, a starter common to all of said motors, said starter comprisinga resistance in series with the armature of each of said motors, acontactor for closing the armature circuits and contactors for cuttingout said resistance, a retarded relay controlling said contactors foroperation in sequence, a control circuit including the coil of saidrelay, one of said contactors adapted, in closing, to open the circuitto said coil and connect a holding circuit for its own coil to saidcontrol circuit, overload switches connected in series in said controlcircuit, one

.switch for each motor, and a coil in the armature circuit of each motorfor opening one of said switches in case the motor is overloaded,whereby an overload current in any of the armature circuits will causethe opening of the control circuit and stoppage of all of said motors.

5. In a refrigerating system, a first motor, a second plurality ofmotors, a starter common to all of said motors, said startercomprislng-a resistance in series with the armature of each of said motors, acontactor for closing the armature cir wits and contactors for cuttingout said resistance, a retarded r lay controlling said contactors foroperation in sequence, a control circuit including the coil of saidrelay, one of said contactors adapted, in closing, to open the circuitto said coil and connect a holding circuit for its own coil to saidcontrol circuit, overload switches connected in series in said controlcircuit, one switch for each motor, and a thermostat switch, a highpressure switch and a low voltage relay switch in series in saidcircuit; whereby the opening of any of said switches will cause thestoppage of all of said motors.

6. In a refrigerating system, a storage battery, a variable speedgenerator for charging the battery, a motor, a starter for connectingthe motor to the battery circuit, a control circuit for controlling theoperation of the starter, a low-voltage relay having an energizing coil,a circuit for conmeeting said coil to the battery circuit including anormally open switch, said relay, when its coil is energized, adapted toclose the control circuit ii the battery voltage is above apredetermined value and to open said control circuit if the batteryvoltage falls below said value, and means for automatically reclosingsaid relay, after it has opened by failure of battery voltage, if thegenerator voltage rises above the battery voltage.

7. In a refrigerating system, a storage battery, a variable speedgenerator for charging the battery, a motor, a starter for connectingthe motor to the battery circuit, a control circuit for controlling theoperation of the starter, a low-voltage relay having an energizing coil,a circuit for connecting said coil to the battery circuit including anormally open switch, said relay, when its coil is energized, adapted toclose the control circuit if the battery voltage is above apredetermined value and to open said control circuit ii the batteryvoltage falls below said value, means for automatically reclosing saidrelay, after it has opened by failure of batteryvoltage, ii the generator voltage rises above the battery voltage, comprising a contactorhaving a coil responsive to generator voltage, means for connecting saidcoil to the generator when the voltage of the latter rises above thebattery voltage, and a circuit controlled by said'contactor forconnecting the energizing coil of the relay to the generator.

8. In a refrigerator system, a storage battery,

a variable speed generator for charging the battery, a driven member, afirst direct current motor for operating the driven member, a seconddirect.

current motor, a starter common to both of said motors, said startercomprising a resistance in series with the armature of each of saidmotors. a contactor for closing the armaturecircuits and contactors forcutting out said resistance, a retarded relay controlling saidcontactors for operation in sequence, a control circuit including thecoil of said relay, one of said contactors adapted, in closing, to openthe circuit to said coil and connect a holding circuit for its own coilto said control circuit, overload switches connected in series in saidcontrol circuit, one switch for each motor, and a thermostat switch, ahigh pressure switch and a low voltage relay switch in series in saidcircuit, an alternating current motor adapted for operating said drivenmember and for operating said first motor as a generator, a manuallyoperable switch for connecting the circuits of said alternating currentmotor to a supply circuit, and a normally open relay for closing thecircuits of the alternating current motor, said relay having anoperating coil included in the aforesaid con trol circuit.

J 1". mass.

